Solid-state thermoelectric converters are recently receiving increasing attention due to their potential to make important contributions to the effort on reducing CO2 and greenhouse gas emission and providing cleaner forms of energy. Such converters utilize thermoelectric materials, that is, materials that show the thermoelectric effect in a strong and/or convenient form. Thermoelectric effects involve direct conversion between thermal and electrical energy by employing electrons and holes as the energy carriers, which can be used, for example, for waste heat recovery, and for thermal management of microelectronics and biological systems. The energy conversion efficiency of thermoelectric devices is governed by the dimensionless thermoelectric figure-of-merit (ZT), where a ZT value of about 1 has been a benchmark for many thermoelectric materials.